Method for manufacturing conductive adhesive for high frequency flip chip package applications

Abstract

Disclosed is a method for manufacturing a low dielectric constant conductive adhesive that is appropriate for a radio frequency packaging application. This method is characterized by mixing a thermosetting resin with surface-treated conductive particles and non-conductive particles for prevention of agglutination and thereby forming the conductive adhesive. The manufactured conductive adhesive is useful for a bonding material of the radio frequency packaging. According to the present invention, it is possible to obtain a flip chip bonding having superior mechanical and electrical performance compared with the conventional flip chip bonding art. Also, since the adhesive has a low high frequency loss and a low dielectric constant, it is possible to realize a flip chip package having a superior electrical performance. The conductive adhesive is particularly useful for the flip chip packaging of a device having a bandwidth of microwave and millimeter wave.

What is claimed is:  
     
       1. A method of manufacturing a conductive adhesive for a high frequency flip chip package application, the method comprising: 
       a first step of preparing a resin compound by mixing 15-25% by weight bisphenol A epoxy resin in a solid state, 40-50% by weight bisphenol F epoxy resin in a liquid state, and 30-40% by weight phenoxy resin;  
       a second step of agitating and mixing the resin compound with an organic solvent in which methyl-ethyl ketone and toluene are mixed in a volume ratio of 1:3, to form a thermosetting resin;  
       a third step of mixing the thermosetting resin with conductive particles and non-conductive particles that have been surface treated in methyl-ethyl ketone or γ-glycidoxypropyl-trimethoxysilane; and  
       a fourth step of mixing a resulting composition of the third step with an imidazole-based hardener in an amount of 15-30 g of imidazole-based harder per 100 g of epoxy resin contained in the resulting composition for prevention of agglutination.  
     
     
       2. The method of  claim 1 , wherein the second step is carried out at a temperature range of 85-95° C. for 24-36 hours. 
     
     
       3. The method of  claim 1 , wherein the conductive particle is comprised of nickel, copper, or gold-coated polymer ball. 
     
     
       4. The method of  claim 3 , wherein the conductive particles have a size ranged from 4-10 μm. 
     
     
       5. The method of  claim 1 , wherein the non-conductive particle is comprised of one selected from the group consisting of SiO 2 , PTFE, and nano-void. 
     
     
       6. The method of  claim 5 , wherein the non-conductive particles has a size of less than 1 μm in diameter. 
     
     
       7. The method of  claim 1 , between the third step and the fourth step, further comprising a step of adding γ-glycidoxypropyl-trimethodxysilane to the resulting composition of the third step to prevent agglutination of the particles. 
     
     
       8. The method of  claim 1 , after the fourth step, further comprising a fifth step of placing the resulting composition of the fourth step in a vacuum state to remove impurities including voids. 
     
     
       9. The method of  claim 8 , after the fifth step, further comprising a step of forming a film having a constant thickness on a releasing paper film by applying a doctor blade method, or a comma roll method to the resulting composition of the fifth step. 
     
     
       10. The method of  claim 9 , wherein the film shaped adhesive has a thickness ranged from 10 μm to 50 μm.